A typical grinding mill comprises a generally cylindrical drum with openings at one or both ends of the drum. Spaced about the inside wall of the drum are a number of lifter bars which are elongate objects which stand proud of the inner drum surface. The material to be ground is introduced to the drum along with grinding media in the form of a number of steel balls. The drum is caused to rotate and, as it does so, the lifter bars serve to lift the material and grinding media as the drum rotates, rather than merely sliding along the inside wall of the drum. At a certain point in the rotation of the drum, the material and grinding media falls away from the lifter bar by action of gravity to impact at the lower region of the drum. The force of the impact causes the material to be broken into smaller pieces thus effecting a grinding action.
The lifter bars become worn during operation of the mill and have a limited service life. It is necessary to replace the lifter bars from time to time. The lifter bars can weigh of the order of 200 kg, and often the openings at the ends of the drum through which the lifter bars must pass provide very limited clearance.
There remains a need for improvements to ease the process of installation and removal of lifters bars into and out of a grinding mill.